The present invention relates to a brake disc-hub connection wherein a hub has drivers which extend from a wheel flange of the hub in the axial direction relative to a rotational axis common to a brake disc and the hub and which engage in a tooth-like manner between supporting elements which are arranged on the inner circumference of a brake disc and which extend in the direction of the rotational axis.
For improving the thermal crack resistance of brake discs it has proved advantageous if the friction ring of the brake disc is able to expand radially and is designed symmetrically. To this end there are various proposals in the prior art. Thus a generic brake disc-hub connection is disclosed in DE 199 18 069 A1 in which the connection of the brake disc to the hub takes place by use of tooth-like elements on the hub and on the brake disc which engage in one another and which ensure a transmission of the braking torque from the brake disc to the hub.
In this case, the teeth have a significant wedge shape. If the brake disc is subjected to high temperatures it may lead to internal component stresses which allow the brake disc to shrink slightly in diameter. In this case, the wedge shape of the teeth may lead to a clamping of the brake disc in the connection thereof which impedes, on the one hand, the thermal expansion and, on the other hand, the servicing relative to the dismantling of the components.
In particular for easier dismantling, solutions are disclosed in DE 10 2009 019 420 A1 or the aforementioned DE 199 18 069 A1 in which intermediate elements are provided between the tooth-like elements engaging in one another on the hub and the brake disc, the dismantling being simplified thereby.
For reducing a heat input caused by a braking procedure, it is disclosed for example in DE 10 2008 014 857 A1 to insert intermediate elements between the teeth of the brake disc and/or the hub, a direct heat transfer being prevented thereby.
It is the object of the present invention to provide a brake disc-hub connection with an improved capacity for servicing and a further reduced heat input.
This and other objects are achieved by a brake disc-hub connection according to the invention, in which a hub has drivers which extend from a wheel flange of the hub in the axial direction relative to a rotational axis common to a brake disc and the hub and which engage in a tooth-like manner between supporting elements which are arranged on the inner circumference of a brake disc and which extend in the direction of the rotational axis. Lateral flanks of the drivers are oriented radially to the rotational axis or parallel to a radial line and lateral flanks of the supporting elements are oriented parallel to the lateral flanks of the drivers, wherein the lateral flanks of each of the drivers are oriented at an angle of 15° to 30° to each other. Preferably, the lateral flanks of each of the drivers viewed from the rotational axis (A) are oriented at an angle of 15° to 30° to one another.
By the radial or at least approximately radial orientation of the lateral flanks of the drivers to the rotational axis, a brake disc-hub connection is provided in which the braking forces occur in the interface between the hub and the brake disc almost exclusively as purely normal forces.
By the orientation of the lateral flanks of the drivers of the hub such that the tangents thereof meet in the rotational center of the hub and/or inside an area of a circle, the centerpoint thereof being the rotational center the hub, and with a corresponding design of the lateral flanks of the brake supporting elements of the brake disc, the braking torque is transmitted into this toothing virtually as a purely normal force. The tangents of the lateral flanks of the supporting elements of the brake disc, therefore, either meet in the rotational axis or—with a use of intermediate elements which form the subject of some of the subclaims—on or in a circle with double the diameter of the corresponding double thickness of the intermediate elements.
The tooth shape which has thus been altered of the drivers and the supporting elements also reduces the wedge effect of the brake disc toothing and, as a result, the clamping of the brake disc.
The orientation of the lateral flanks of each of the drivers at an angle of 15° to 30° ensures the transmission of high braking torques. The width of the drivers in the circumferential direction is, therefore, defined by the size of the angle between the lateral flanks of the driver. The larger this angle, the more rigid the toothed connection.
However, with an angle which increases in size, the intermediate space which is available between two such drivers for ventilating the brake disc is smaller. It has proved advantageous that an angle of between 15° to 30° determining the width of the drivers is optimal with regard to the rigidity required for the transmission of the braking torque and with regard to a sufficiently large intermediate space for ventilating the brake disc.
Particularly preferably, the lateral flanks of each of the drivers, viewed from the rotational axis, in this case are oriented at an angle of 23° to 25°, in particular of 24°, to one another.
According to one variant, the drivers are configured as front ends of support webs extending axially away from the wheel flange.
According to a preferred variant of the invention, a push-on stop is integrally formed on at least one of the lateral flanks of each of the drivers, for axially fixing the brake disc. This permits additional components and mounting effort on the hub and/or the brake disc, for the axial fixing of the brake disc on the hub, to be dispensed with.
In a further variant, each of the support webs has slots extending axially from the driver in the direction of the wheel flange to form lateral support webs, wherein the front faces of the free ends of the support webs are configured as a push-on stop for axially fixing the brake disc.
By the thermal separation formed thereby between the push-on stop, the supporting elements of the brake disc heated during a braking procedure bearing thereagainst during operation, and the respective driver, a reduction of stresses is possible due to the variable temperatures of the brake disc relative to the hub.
According to a further variant of the brake disc-hub connection according to the invention, first intermediate elements are arranged in the intermediate spaces between the lateral flanks of the drivers and the supporting elements, said first intermediate elements encompassing the drivers in a radial and U-shaped manner in the circumferential direction and bearing at least against the opposing flanks of the drivers in a planar manner. The U-shaped design of these intermediate elements in this case permits a particularly simple mounting.
According to a further preferred variant, second intermediate elements are arranged between the lateral flanks of the supporting elements and the arms of the first intermediate elements bearing against the lateral flanks of the drivers, said second intermediate elements being able to be mounted separately between the first intermediate elements.
These second intermediate elements are particularly preferably configured as angled elements with two arms oriented at an angle, in particular at right-angles to one another, wherein in the mounted state a first arm is clamped between the lateral flank of one of the supporting elements and the lateral flank of one of the first intermediate elements and a second arm bears against the front face of the supporting element applied to the wheel flange of the hub.
A further improved thermal insulation between the brake disc and the hub is permitted by the introduction of two separate intermediate elements between the flanks of the drivers and the supporting elements. Moreover, two such separately mountable intermediate elements also contribute to improving the ease of servicing (in particular when replacing the brake disc).
In order to avoid adhesion of the two intermediate elements bearing against one another by the action of moisture, the first and second intermediate elements preferably consist of a non-rusting material or are provided with a non-rusting coating, so that the first and second intermediate elements may be easily mounted and/or dismantled when installed and also when dismantled.
Additionally, such non-rusting materials and/or non-rusting coatings have a low coefficient of friction which in the case of servicing permits a simple axial connection of the brake disc.
According to a further preferred variant, in the region of the brake disc-hub connection the first intermediate elements form a separating layer between the brake disc and the hub. To this end, particularly preferably the free ends of the arms of the first intermediate elements extending approximately radially to the rotational axis are configured as separating webs bent back outwardly and extending axially to the rotational axis, in each case a lower face of the supporting elements extending axially to the rotational axis or a lower edge of the first arm of the second intermediate element being able to be supported on said separating webs.
Additionally, preferably separating surfaces are integrally formed on the lateral arms of the first intermediate elements on a side facing the wheel flange of the hub, said separating surfaces being oriented parallel to the plane of the brake disc and covering a push-on stop integrally formed on the hub and axial to the rotational axis, for the axial fixing of the brake disc relative to the brake disc.
By the first intermediate elements configured with such projections, an improved thermal insulation of the brake disc from the hub is ensured, since the brake disc is insulated relative to the hub on all contact surfaces, by the first intermediate element being positioned on the driver of the hub.
According to a further preferred variant, the transitions between the separating webs and the arms of the first intermediate elements extending approximately radially to the rotational axis are configured as depressions, respective lower edges of the first arm of the second intermediate elements being able to be supported in said depressions by being inserted therein.
As a result, the lower edges of the first arm of the second intermediate elements are additionally secured against slippage in the circumferential direction relative to the rotational axis of the brake disc.
Preferably, the first and the second intermediate elements are positively connected together. Particularly preferably, openings are formed on a region of the separating surfaces in the vicinity of the lateral arms of the first intermediate elements, in each case a nose of one of the second intermediate elements extending therethrough in the mounted state, wherein the nose extends from the end of the first arm spaced apart from the second arm.
As a result, the second intermediate elements are effectively prevented from migrating radially to the rotational axis of the brake disc after mounting on the first intermediate elements.
According to a further preferred variant, a spring element is able to be fastened on a side of the drivers remote from the wheel flange of the hub for axially fixing the intermediate elements.
In order to achieve sufficient ventilation of the brake disc, the hub preferably has a total of three, four or five drivers and the brake disc correspondingly has six, eight or ten supporting elements.
As a result, it is possible, in particular, to provide larger recesses between the supporting elements of the brake disc (in comparison with those brake discs known from the prior art with a considerably greater number of supporting elements), whereby the cool air cross section is considerably enlarged.
According to a further preferred variant the hub has a wheel flange extending radially outwardly to the rotational axis, the drivers extending axially therefrom to the rotational axis.
In a preferred variant, the hub has a pot-like hollow-cylindrical portion which merges with the wheel flange extending radially outwardly to the rotational axis, wherein the drivers are supported by webs rising radially outwardly from the pot-like portion and extending axially toward the wheel flange.
The axial extent of the drivers away from the wheel flange of the hub in this case also contributes to improved thermal insulation of the brake disc relative to the hub.
Exemplary embodiments of the invention are described in more detail hereinafter with reference to the accompanying drawings, in which:
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.